Dry cleaners often have a difficult time explaining to customers invisible stains, set stains, fabric flaws, fabric limitations, and other damage to garments, upholstery, and rugs to be cleaned. In the past, cleaners have used light to reveal stains in fabrics, to reveal fabric weak areas, and to identify stains within fabrics. The use of light for identifying stains and fabric flaws has been helpful to personnel in textiles, dry cleaners, garment analysts, museum curators, conservators, restorators, and manufacturers and retailers of clothing, textiles, and upholstered furniture. A stain detector apparatus would be useful to identify stains and flaws in fabrics.